The present invention relates to a rotating electric machine of four poles and an armature winding of three-phase circuit thereof formed with three winding circuitry every each phase in parallel and mounted in double-layer winding in several slot provided in a stator core.
For example, in Japanese Patent Laid-open 9-205750 bulletin, a rotating electric machine in which voltage unbalance between winding circuitries is improved by specially arranging a coil constituting each winding circuitry in case of number 72 of a stator slot, is disclosed.
When the coil constituting each winding circuitry is connected with a coil end, if all winding pitch cannot be constant, a winding pitch of the specified coil is changed as mentioned in Japanese Patent Publication No. 54-6683 bulletin, for example.
Conventionally, for example, in a rotating electric machine of three-phase, four poles, stator slot number 72, a coil arrangement that voltage unbalance between three winding circuitries becomes small is suggested, and the slot number is limited to be 72. Therefore, according to the capacity increasing of the generator, when the slot number is reduced than 72, it is necessary to find a suitable coil arrangement for the slot number.
In a rotating electric machine of three-phase circuit, four poles, stator slot number 63, having an armature winding in which three winding circuitries connected in parallel, every each phase, an object of one of this invention is to provide the armature winding of the rotating electric machine and the rotating electric machine that the voltage unbalance between the winding circuitries of each phase is small and edge construction of the armature winding does not become complicated.
In order to achieve the above object, according to an aspect of the present invention, in a case of a three-phase circuit and stator slot number 54, four poles P1, P2, P3, P4 are constituted with first to third winding circuitries in each phase as follows.
Pole P1: said first winding circuitry provided with all five top coils and bottom coils,
pole P2: said first winding circuitry provided with third top coil and a bottom coil from a winding axis of the pole P2, and said third winding circuitry provided with first, second and fourth top coils and bottom coils from said winding axis of the pole P2,
pole P3: said second winding circuitry provided with all five top coils and bottom coils, and
pole P4: said second winding circuitry provided with a third top coil and a bottom coil from a winding axis of the pole P4, and said third winding circuitry provided with first, second and fourth top coils and bottom coils from said winding axis of the pole P2.
As the each winding circuitry does not provided more than three poles each three, when the winding circuitry of said each phase is constituted as above, there is no need to increase a number to cross over, and the voltage unbalance between each winding circuitries can be turned into 1.5% around, too. Thereby, in a rotating electric machine of four poles and three-phase comprising the slots less than 63 and an armature winding mounting in parallel the three winding circuitry every each phase, it is provided an armature winding of a rotating electric machine and a rotating electric machine in which the voltage unbalance between winding circuitries of each phase is small and an edge construction of the armature winding does not become complicated.
According to another aspect of the present invention, a rotating electric machine of four pole provided with a three-phase and star connection, each of said three-phase being constructed with three winding circuitries in parallel, having a stator core provided with slots of 9n (2xe2x89xa6nxe2x89xa67) pieces, each of said slot being provided with double-layer windings, further comprises two of said four poles in said each phase being constituted with only one of said three winding circuitries.
According to another aspect of the present invention, a rotating electric machine of four pole provided with a three-phase and star connection, each of said three-phase being constructed with three winding circuitries in parallel, having a stator core provided with slots of 54 pieces, each of said slot being provided with double-layer windings, further comprises two of said four poles in said each phase being constituted with only one of said three winding circuitries.
The rotating electric machine such as a generator has a stator and a rotor, the stator core constructed with thin plates of multi-layer, and plural slots are provided in the internal circumference side of the stator in order to wind the armature winding. In the generator, as it is desirable for the waveform of the induced voltage to be complete sine wave shape, magnetic flux density distribution of air gap should be a sine-wave form. When the armature winding is provided with a concentrated winding, the magnetic flux density distribution becomes to be a square wave, and it is quite different from a sine-wave distribution. Accordingly the armature winding should be provided with a distributed winding.
On the other hand, the windings that the winding pitch is equal to a pole pitch, is called as a full pitch winding, the windings that the winding pitch is shorter than the pole pitch, is called as a short-pitch winding. Generally, the generator is provided with the short-pitch winding in order to bring the magnetic flux density distribution close to the sine-wave form further.
In case of a turbine generator, a dipoles machine is mostly used in the thermal power generator, however a four pole machine is used in an atomic-power generator. Generally an armature winding of the turbine generator is Y connection, the number of the winding circuitry every each phase becomes to be a divisor of the number of the poles. This is because when the number of the winding circuitry of each phase is the divisor of number of pole, as the coil which constitutes each winding circuitry is capable to be provided with completely the same arrangement electrically, and it becomes possible to make the induced voltage between each winding circuitry balanced.
By the way, when the number of the winding circuitry every each phase is three, the construction of the generator can be streamlined than a case in the four line circuitry. However, in the four pole machine, because the number of the winding circuitry of the armature winding is not a devisor of the number of the poles, the induced voltage of the three winding circuitry apt to be unbalance. Accordingly when the number of the winding circuitry of each phase is provided with 3 in the four pole machine, it is necessary for the voltage unbalance between the winding circuitry to become small.
In late years, a single capacity of the generator is in an increasing trend, and when the capacity of the generator becomes big, because the power factor is almost the same, the product of the voltage and the current of the generator should be increased. However, by a proof pressure of insulation to be used for the coil of the armature winding, terminal voltage of the generator is limited. In such a case, the terminal voltage is held down by reducing the number of the stator slot, and the armature current is provided to be big. That is to say, if the number of the slot is reduced, number of the top coil and the bottom coil constituting one winding circuitry decreases, and the terminal voltage is capable not to be high, it becomes possible to make the cross section of the coil big and to make armature current big, because the slot width can be broad according to the decreasing of the number of the slot.